Tap.



S. DUPRE, JR. TAP.

APPLICATION rum) QGT. 11, 1913.

1,095,716. Patented May 5,1914.

WITN ESSL S: INVENTOR. J a W. 5@M% A! diam. BY

ATTORNEYAS.

STEPHEN DUPRE, JR., OF SPRINGFIELD, MASSACHUSETTS.

TAP.

To all whom it may concern Be it known that I, STEPHEN Duran, J12, acitizen of the United States of America, residing at S ringfield, in thecounty of Hampden anc State of Massachusetts, have invented a new anduseful Tap, of which the following is a specification.

My invention relates to improvements in tools used for cutting internalscrew-threads, and more particularly to hand-operated taps, and consistsof a tap equipped with a screwthreaded shank that has a thread of thesame pitch as is that of the tap threads or cutting elements of the tap,which shank has thereon or is provided with a work-engaging member, allas hereinafter set forth.

In tapping holes by hand it is very difficult, not to say impossible, tokeep the tap perpendicular to the plane of the work, so as to produce anopening with screw-threaded sides the axis of which threaded opening isabsolutely perpendicular to the aforesaid plane, and it not infrequentlyoccurs that some of the threads cut by the tap are stripped, and theprimary object of my invention is to produce a tap or provide a tap withmeans wherewith or whereby both of these difficulties are entirelyremoved or avoided. This is accomplished by reason of the fact that thework-engaging member is tight against the work all the time, travelingtoward the tap cutters as fast as the latter enter the work, andconsequently compels the tap to move in a line perpendicular to theplane of the said work; and at the same time the tap is relieved of muchof the strain to which it is ordinarily subjected.

Other objects and advantages will appear in the course of the followingdescription.

I attain the objects and secure the advantages of my invention by themeans illus trated in the accompanying drawings, in which- Figure 1 is aside elevation and partial section of a tap which embodies a practicalform of my invention, showing the application of the same to a piece ofwork; Fig. 2, an elevation of the working end of said tap without thenut, and, Fig. 3, a side elevation and partial section of a modifiedform of construction.

Similar figures refer to similar parts throughout the several views.

In all three of the views a tap, comprising a shank 1 and cutter 2, isshown. Thus far the tap does not differ in any essential Specificationof Letters Patent.

Application filed. October 11, 1913.

Patented May 5, 1214.

Serial No. 794,618.

particular from an ordinary implementfor the same purpose. The head ofthe shank l is made angular in cross-section, as shownat 3, to afford abearing for a tap wrench.

In what is believed to be the preferred construction of the invention,that illustrated in the first two views, I extend the cutter 2 orprovide the same with an axial rojection, stud or post 4, beyond the leaing terminal of said cutter, and provide such post with a screw-thread 5having the same pitch as that of the cutter 2, and also the samedirection. Fitted to the post 4 is a nut 6, which has its inner faceconcaved, as represented at 7 to receive the leading end of the cutter 2and thus enable said cutter to pass clear through the work and completethe thread cut thereby. Preferably the nut 6 is winged to make of it athumb nut.

In Fig. 1 appears in section a piece of work 8 which has an o enin 9therein that is in the act of being tapped. In practice, the post 4 ispassed through the opening 9, and the nut 6 is screwed on to theterminal of said post that protrudes from said opening. The nut 6 isscrewed tightly against one side of the piece of work or block 8,drawing the leading end of the cutter 2 into close contact with saidblock on the other side thereof or atthe opposite end of the opening 8over or under which said nut is placed, and thus said block at thebeginning is em braced between said cutter and said nut. Since the planeof the work-bearing portion of the nut 6 is at right-angles to the axisof the tap and its parts, the post 4t occupies the center of the opening9, with the axis of the two coinciding, and, since the axis of said postis a continuation of the axis of the cutter 2, the latter can notdeviate from a direct course during the tapping operation, provided saidnut is actuated toward said cutter as fast as the latter advances, asmust be the case owing to the fact that the pitch of the thread 5 is thesame as that of the threads at 2. WVhen the nut 6 is properly setagainst the block 8, a wrench is applied to the bearing 3 and the shank1 with the cutter 2, together with the post 4, is rotated in the properdirection to cause said cutter to enter the opening 9 and cut threads inthe sides thereof, the tapping operation itself being no difierent fromthat performed by any ordinary tap. As the cutter 2 advances, the post4t also advances through the nut 6 and retains said nut in its originalposition opening. At the end of the operation the nut 6 is unscrewedfrom the post 41: and the cutter 2 turned out of the now threadedopening 9. In this first construction all of theparts, with theexception of the nut, are by preference integral with each other.

Instead of employing a fixed post or extension at the leading end of thecutter 2, with a movable nut thereon, I may employ a mo *ablc extensionor post 10 having thereon a fixed nut or head 11, such post being tappedinto the cutter portion of the shank 1, as shown in Fig. 3. The member10 and he bore therefor in the shank 1 are respectively provided withscrew-threads 12 and 13, the pitch of which in each case correspondswith that of the cutter 2. The direction of the screw-threads 12 is alsothe same as that of the cutter threads. The head 11 is recessed in thesame way and for the same purpose as is the nut 6. The operation of themodified construction is the same as in the other case, except that thecutter, while in the actof tapping a hole, advances on the extension orpost 12 toward the head 11, instead of carrying with it thescrew-threaded extension and causing the latter to advance through theworkengaging member or nut.

\Vhile the second or modified construction is entirely practicable andquite as efficient perhaps as the other, it is believed that a strongerand more du "able device is produced wh n a fixed extension, for anindependently movable nut, is provided at the leading end of the cutter,in the manner substantially as shown in Fig. 1.

Various changes in the form, proportions, and details of construction,other than are shown and described, may be resorted to without departingfrom the principle or exceeding the scope of this invention, except asset forth in the claims.

What I claim as my invention, and desire to secure by Letters Patent, is

1. As a new article of manufacture, a tap provided at the cutterterminal with an extension having a screw-thread of the same pitch asthat of the cutter, and a work engaging member on said extension andadapted to bear only on the outside of the work.

2. As a new article of manufacture, a tap provided at the cutterterminal with an eX- tension having a screw-thread of the same pitch asthat of the cutter, and a work-engaging member on said extension, thesur face or said member, which is contiguous to the work, being recessedto receive the leading end of said cutter, and said work-engaging memberbeing adapted to bear on the outside of the work.

3. As a new article of manufacture, a tap provided at its cutterterminal with a post having a screw-thread of the same pitch as that ofthe cutter, the diameter of such post being smaller than that of saidcutter, and a work-engaging member carried by said post and adapted tobear only on the outside of the work.

4. As a new article of manufacture, a tap provided at the cutterterminal with a fixed post having a screw-thread of the same pitch asthat of the cutter and being of less diameter than said cutter, and awork-engaging member carried by said post, said member having a recesstherein to receive the lead ing end of said cutter, and being adapted tobear only on the outside of the work.

5. As a new article of manufacture, a tap provided at the cutterterminal with a fixed post of less diameter than the cutter and having ascrew-thread of the same pitch as that of said cutter, and a nutthreaded to said post and adapted to bear on the outside of the work.

6. As a new article of manufacture, a tap provided at the cutterterminal. with a fixed post of less diameter than the cutter and havinga screw-thread of the same pitch as that of said cutter, and a nutthreaded to said post, said nut being adapted to bear on the outside ofthe work and recessed to receive the leading end of said cutter.

STEPHEN DUPRE, J R.

Witnesses F. A. CUTTER, A. C. FAIRBANKS.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents,

Washington, D. G.

